loopy, your last post reminded me of something insightful and useful that a friend said/explained to me when my own DS1 was in this stage. She's a qualified psychiatric nurse and youth worker, and parent, and understands more about the workings of the teenage mind than most!
People who grow up learning to try difficult things go through a cycle of emotions: they're scared, they feel awful, they face their fear to try anyway, they succeed and feel great, or they fail but realise that bad feeling passes quickly and they soon feel ok again...
But some people get 'stuck'. They get so scared of failure, or the bad feelings, or trying, that they start avoiding the things that make them feel bad. And because they do this, they never push on through to experience the good feeling of success or to realise the bad feelings will pass again. All they feel is the bad feeling of fear or apprehension, or a state of no-feeling if they can manage to avoid difficult stuff.
This rang so true to me that I explained it to DS1 too, and told him I thought that was what was happening to him. Soon after that, he tried something important for the first time in months: he had a college course he'd wanted to do the year before, but hadn't applied for, and had missed his interview for that year, and the open recruitment day, and the late enrollment day, and reached the last chance final enrollment day... We had an awful, difficult day and he very nearly didn't go, but a combination of encouragement and threats and calm and reminding him of this 'face the fear' process did eventually get him there... And it was a major turning point for him. :)
He still finds it hard to face difficult things, but is at last realizing that the more often he does it, the less awful it feels...